Editing 2469: Astronomy Status Board

{{comic
| number    = 2469
| date      = May 28, 2021
| title     = Astronomy Status Board
| image     = astronomy_status_board.png
| titletext = Junior astronomers hate getting put on board update duty, but someone's gotta make sure that stuff is still up there.
}}

==Explanation==
[[Ponytail]] is staring at the sky through a telescope while [[Cueball]] is operating a checklist, visible on a large screen on what looks like a large billboard.

Since they are junior astronomers, they appear to have been tasked with simply verifying whether normal celestial objects are still present in the sky, such as the Sun and the Moon. Only large objects that are clear in the sky (at least at night for those not the Sun). Although all of these objects will eventually disappear it is not expected to happen within the next hundred years. {{Citation needed}}

This is likely a reference to the many "status boards" for online services ([https://portal.office.com/ServiceStatus example], [https://status.cloud.google.com/ another example], [https://forum.suprbay.org/status a different example], [http://hasthelargehadroncolliderdestroyedtheworldyet.com/ a funnier example]). The joke is that it would be funny if there was a status board to check that all the celestial bodies are still there, and that with our modern culture few people are looking directly at the real sky, even though anyone with a telescope and an unobstructed view could just look at the sky to verify for themselves without referencing such a status board. This is compounded by the fact that the listed celestial bodies have existed for billions of years, and are expected to last for billions more, leading one to wonder why astronomers would bother checking and rechecking just to see if they're "still there" with any sort of regularity.

This comic may also be an oblique reference to the study of the projected future of celestial objects given our current understanding of physics.  At various points in the future the objects on the billboard may become unobservable from Earth.  The Moon is gradually receding from Earth, and when the Sun enters its red giant phase the Moon might be broken up.[https://www.space.com/3373-earth-moon-destined-disintegrate.html]  Eventually the Sun itself will run out of {{w|Sun#After_core_hydrogen_exhaustion|usable fuel}} and will go dark as will other stars.  Moreover, if current theories of dark energy and universal expansion hold, the acceleration of the universe could push galaxies beyond the {{w|Cosmological_horizon#Hubble_horizon|"Hubble Horizon"}}, meaning they would no longer be observable.  Matter itself could even cease to exist under some hypothetical scenarios, such as {{w|Proton_decay|proton decay}} or the {{w|Big_Rip|Big Rip}}.  The joke of the comic here would be that all these scenarios are only possible in the unimaginably far future (exception: {{w|False_vacuum_decay|False Vacuum Decay}} ) and do not need constant monitoring by astronomers.

==Transcript==
:[Ponytail is looking through a telescope, while Cueball is pressing buttons, which makes noises, on a remote control connected with a wire to a large board to their right. He controls the messages shown on this board.]
:Remote: Beep beep

:[The board has a black screen, with a label in a white section above the screen:]
:Astronomy Status Board:

:[The black screen has five rows with text in three columns. The first column is with white text. The second is in glowing green text and the last are in faded grey red text.]
     Moon  '''<font color="green">Still there</font>'''   <font color="gray">Gone</font>
      Sun  '''<font color="green">Still there</font>'''   <font color="gray">Gone</font>
    Stars  '''<font color="green">Still there</font>'''   <font color="gray">Gone</font>
  Planets  '''<font color="green">Still there</font>'''   <font color="gray">Gone</font>
 Galaxies  '''<font color="green">Still there</font>'''   <font color="gray">Gone</font>

==Conditions under which celestial objects might be considered "gone"== 
Astronomers do regularly observe {{w|occultation}}s of stars by other celestial bodies, and sometimes also search through archived images for missed occultations.  This can provide information on the size and orbit of an asteroid too small to observe directly, or other useful scientific knowledge, but occulted stars are not "gone", merely hidden.  There are also a few astronomers who are searching image archives for [https://www.space.com/hunt-for-universe-missing-stars-space-mysteries stars that really have completely vanished without a trace] (or suddenly appeared), as this would be a sign of truly novel physics -- perhaps even a sign of extraterrestrial intelligence -- but no such vanishings have yet been identified. This comic appeared at the time the [https://vasconsite.wordpress.com/ VASCO project] is receiving media attention, claiming that [https://iopscience.iop.org/article/10.3847/1538-3881/ab570f 800 stars visible in 70 years old photos are not seen anymore].

Small stars which have exhausted their hydrogen fuel without building enough heat to fuse carbon or oxygen, are theorized to eventually collapse into faint "{{w|white dwarf}} stars" which are of such low luminosity that they are unlikely to remain visible to the naked eye from the Earth's surface except at very close proximities. The Earth's sun, Sol, is generally expected to follow this progression as a low-mass {{w|main sequence}} star, during the latter period of its {{w|stellar evolution}}. Although some stellar models predict that relatively rapid collapses are possible, the long time scale over which stellar evolutions are believed to occur decreases the odds of observing any one specific star both before and after this transition. In this comic, individual stars are not listed; therefore "gone" is unlikely to be useful for the stars, because a great number of stars would be "still there" until well after the expected collapse of our own sun. 

Larger stars have enough mass and thus gravitational pressure to be able to react the waste products of previous stages, releasing more energy, until it starts fusing iron.  Iron fusion actually absorbs energy which means the energy flow and the gravitational pressure are both going downward and in a few hours, the star with become a supernova, sending most of its mass away from the star with lots of even heavier elements included and crushing anything left in the middle down into degenerate neutron matter, forming a neutron star.  Many neutron stars will continue to glow for millennia, but with no new reactions.  Some neutron stars will have a "hot spot" which on the spinning surface of the neutron star forms a pulsar.  If the original star was large enough, the neutron star will be so massive that it will curve space-time so much that it will become a black hole, which does not emit any light.  In this way, some large stars will disappear, but the process of star formation to supernova to black hole still takes millions of years so is unlikely to be seen in a human lifetime.  Many black holes will develop an accretion disc around them, made of in-falling matter, which will glow in visible to x-ray light; in this way a black hole can still be seen.

One of the proposed outcomes of the ultimate fate of the universe is the {{w|Big Rip}}. If it's correct, all the items on the status board will eventually move from Still There to Gone, beginning with the most distant galaxies and proceeding to the objects in our own solar system (although there will be hardly any time for the board to show Gone for the closest, especially the Moon). This scenario is dramatized in the short story "{{w|Last Contact}}" by Stephen Baxter. 

Collisions between celestial bodies are commonly postulated as a fundamental part of the formation of {{w|planetary nebula}}. Since most mass in the known universe is observed to have a relatively low {{w|albedo}}, the presence of numerous unlit, massy bodies of planetary scale and smaller is strongly indicated. This is corroborated by measurements of orbital deflection detected in many visible stars, hinting at the possibility of large planets orbiting around them, unseen due to distance & low luminosity. The possibility of one or more local planets being "gone" could be attributed to unpredicted collision with another object of similar mass or equivalent velocity. Such a collision is one possible explanation for the sudden & catastrophic disintegration of Earth's moon, Luna, in the novel {{w|Seveneves}} by Neal Stephenson. This hypothetical event forms the premise of this book, during which Earth's whole sky becomes occluded by dust raised by millions of impacts across its surface & eventually by the constant incandescent descent of lunar debris itself. Again however, a single collision with any planet besides the Earth would not remove ''all'' the "Planets" from the Earth's visible night sky, so "gone" remains unlikely to be used for that category of celestial objects. 

Occlusion of Earth's entire sky, due to airborne dust, volcanic ash, increased cloud cover, {{w|light pollution}}, or sufficiently dense layers of high-albedo material in orbit, may be the least unlikely potential reason for all of these celestial phenomena to be flagged as "gone". Notably, the phenomena in question would remain; only our view of them would be gone.

{{comic discussion}}

[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring Cueball]]
[[Category:Astronomy]]
[[Category:Comics with color]]